9.3 Chemical Handling, Inventory, Feed Systems & Spill Response

9.3 Chemical Handling, Inventory, Feed Systems & Spill Response

Exam Focus: Three criteria tasks converge here: maintain all equipment (e.g., pumps, motors, chlorinators, chemical feeds) in accordance with SOP/OEM specifications, maintain an inventory of chemicals and materials, and engage in the proper safety procedures for chemical spill responses and hazardous materials.

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Chemicals Used in a Collection System

Ferric chloride deserves a specific note: it freezes or crystallizes at temperatures well above the freezing point of water, so tanks and feed lines must be heated or heat-traced in cold climates. A crystallized line stops the sulfide control program without any alarm.

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Chemical Feed Equipment

Metering pumps. Most collection system dosing uses a diaphragm metering pump, adjustable by stroke length and stroke frequency, or a peristaltic (hose) pump, which isolates the chemical inside the tube and handles gassy or crystallizing liquids well.

A properly built feed system includes:

• Day tank with level indication, sized for a manageable quantity.
• Calibration column — a graduated cylinder plumbed so the pump can be switched to draw from it.
• Back-pressure valve to give the pump a consistent discharge pressure so its output is repeatable.
• Anti-siphon valve to prevent the chemical from siphoning into a lower injection point when the pump stops.
• Pressure relief discharging back to the tank, protecting the pump against a blocked line.
• Injection quill placed to disperse the chemical into the flow stream rather than run along the wall.
• Chemical-compatible materials throughout — the wrong elastomer in a ferric chloride line fails quickly.

Calibration

Feed rate is verified, not read off the dial:

1. Switch pump suction to the graduated calibration column.
2. Run the pump for a measured interval and record the volume drawn down.
3. Convert to the operating rate and compare to the required rate (Section 6.4).
4. Adjust stroke and frequency, then repeat until the delivered rate matches.

Calibrate on a schedule, after any adjustment, and after any maintenance. Record every calibration.

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Storage, Incompatibility, and Containment

Never mix sodium hypochlorite with acid. The reaction liberates chlorine gas, and it has killed water and wastewater workers — commonly when a delivery driver pumps one chemical into the wrong fill connection. Prevention is physical: unique and labeled fill connections, keyed or differently sized couplings, delivery supervision, and clear signage.

Other rules:

• Segregate incompatibles. Acids away from bases; oxidizers away from organics and fuels.
• Secondary containment must hold at least 110% of the volume of the largest container within it, and containment for incompatible chemicals must be separate so a double failure cannot combine them.
• Label everything, including transfer containers. An unlabeled container is a violation and a genuine hazard.
• Ventilation in chemical rooms, plus eyewash and a safety shower within the distance required by the standard, tested regularly.
• Temperature control — freeze protection for ferric chloride, heat protection for hypochlorite, which decomposes and loses strength rapidly when warm.

Hazard Communication

Under the OSHA Hazard Communication Standard (29 CFR 1910.1200), the employer must maintain a written program, keep a safety data sheet (SDS) accessible for every hazardous chemical on site, label containers with GHS pictograms and signal words, and train employees at assignment and whenever a new hazard is introduced.

An SDS has 16 standardized sections in a fixed order. The ones an operator uses under pressure:

• Section 2 — Hazard identification (pictograms, hazard statements)
• Section 4 — First-aid measures
• Section 6 — Accidental release measures (spill response)
• Section 7 — Handling and storage (including incompatibilities)
• Section 8 — Exposure controls and personal protection

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Inventory of Chemicals and Materials

The criteria name inventory maintenance as its own task because a stockout stops a program.

• Set minimum and maximum levels and a reorder point for each chemical, accounting for supplier lead time.
• Track usage rates against dosing records; a sudden rise in usage at constant flow means a leak, a miscalibrated pump, or an increased sulfide load worth investigating.
• Observe shelf life and rotate stock first-in, first-out. Sodium hypochlorite in particular loses strength continuously, so an old drum delivers less active chemical than the dose calculation assumes.
• Maintain the critical spare parts inventory alongside the chemicals: pump tubes, diaphragms, seals, gaskets, check valves, fuses, and a spare metering pump for each service.
• Keep the inventory list aligned with the SDS library and with the local emergency planning committee reporting the jurisdiction requires.

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Chemical Spill Response

1. Protect yourself first. Identify the material if it can be done from a safe distance. Do not approach an unknown release.
2. Evacuate and isolate. Establish a perimeter upwind and uphill; keep others out.
3. Consult the SDS, Section 6.
4. Don appropriate PPE — the SDS specifies it. Ordinary work clothing is not chemical protection.
5. Stop the source if it can be done safely — close a valve, upright a container, plug a leak.
6. Contain. Use absorbent booms, socks, and pads or a soil dike. Never wash a spill to a drain, an inlet, or the sewer. Doing so converts a contained spill into a discharge and, with an incompatible chemical, into a reaction inside the collection system.
7. Neutralize or absorb per the SDS; collect the residue as the waste stream it now is.
8. Notify. Internal chain first, then external as required — the National Response Center if a CERCLA reportable quantity is released, the state environmental agency, and the local emergency responders.
9. Document the material, quantity, cause, response, and disposal, and investigate the root cause.
10. Decontaminate people, PPE, and equipment before returning to service.